| Message ID | 20190529174318.22424-5-amir73il@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Fixes for major copy_file_range() issues | expand |
On Wed, May 29, 2019 at 08:43:08PM +0300, Amir Goldstein wrote: > The access limit checks on input file range in generic_remap_checks() > are redundant because the input file size is guaranteied to be within "guaranteed"... > limits and pos+len are already checked to be within input file size. > > Beyond the fact that the check cannot fail, if it would have failed, > it could return -EFBIG for input file range error. There is no precedent > for that. -EFBIG is returned in syscalls that would change file length. > > With that call removed, we can fold generic_access_check_limits() into > generic_write_check_limits(). > > Signed-off-by: Amir Goldstein <amir73il@gmail.com> Once the changelog is fixed, Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> --D > --- > mm/filemap.c | 33 ++++++++++++--------------------- > 1 file changed, 12 insertions(+), 21 deletions(-) > > diff --git a/mm/filemap.c b/mm/filemap.c > index a38619a4a6af..44361928bbb0 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -2895,24 +2895,11 @@ EXPORT_SYMBOL(read_cache_page_gfp); > * LFS limits. If pos is under the limit it becomes a short access. If it > * exceeds the limit we return -EFBIG. > */ > -static int generic_access_check_limits(struct file *file, loff_t pos, > - loff_t *count) > -{ > - struct inode *inode = file->f_mapping->host; > - loff_t max_size = inode->i_sb->s_maxbytes; > - > - if (!(file->f_flags & O_LARGEFILE)) > - max_size = MAX_NON_LFS; > - > - if (unlikely(pos >= max_size)) > - return -EFBIG; > - *count = min(*count, max_size - pos); > - return 0; > -} > - > static int generic_write_check_limits(struct file *file, loff_t pos, > loff_t *count) > { > + struct inode *inode = file->f_mapping->host; > + loff_t max_size = inode->i_sb->s_maxbytes; > loff_t limit = rlimit(RLIMIT_FSIZE); > > if (limit != RLIM_INFINITY) { > @@ -2923,7 +2910,15 @@ static int generic_write_check_limits(struct file *file, loff_t pos, > *count = min(*count, limit - pos); > } > > - return generic_access_check_limits(file, pos, count); > + if (!(file->f_flags & O_LARGEFILE)) > + max_size = MAX_NON_LFS; > + > + if (unlikely(pos >= max_size)) > + return -EFBIG; > + > + *count = min(*count, max_size - pos); > + > + return 0; > } > > /* > @@ -2963,7 +2958,7 @@ EXPORT_SYMBOL(generic_write_checks); > /* > * Performs necessary checks before doing a clone. > * > - * Can adjust amount of bytes to clone. > + * Can adjust amount of bytes to clone via @req_count argument. > * Returns appropriate error code that caller should return or > * zero in case the clone should be allowed. > */ > @@ -3001,10 +2996,6 @@ int generic_remap_checks(struct file *file_in, loff_t pos_in, > return -EINVAL; > count = min(count, size_in - (uint64_t)pos_in); > > - ret = generic_access_check_limits(file_in, pos_in, &count); > - if (ret) > - return ret; > - > ret = generic_write_check_limits(file_out, pos_out, &count); > if (ret) > return ret; > -- > 2.17.1 >
diff --git a/mm/filemap.c b/mm/filemap.c index a38619a4a6af..44361928bbb0 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2895,24 +2895,11 @@ EXPORT_SYMBOL(read_cache_page_gfp); * LFS limits. If pos is under the limit it becomes a short access. If it * exceeds the limit we return -EFBIG. */ -static int generic_access_check_limits(struct file *file, loff_t pos, - loff_t *count) -{ - struct inode *inode = file->f_mapping->host; - loff_t max_size = inode->i_sb->s_maxbytes; - - if (!(file->f_flags & O_LARGEFILE)) - max_size = MAX_NON_LFS; - - if (unlikely(pos >= max_size)) - return -EFBIG; - *count = min(*count, max_size - pos); - return 0; -} - static int generic_write_check_limits(struct file *file, loff_t pos, loff_t *count) { + struct inode *inode = file->f_mapping->host; + loff_t max_size = inode->i_sb->s_maxbytes; loff_t limit = rlimit(RLIMIT_FSIZE); if (limit != RLIM_INFINITY) { @@ -2923,7 +2910,15 @@ static int generic_write_check_limits(struct file *file, loff_t pos, *count = min(*count, limit - pos); } - return generic_access_check_limits(file, pos, count); + if (!(file->f_flags & O_LARGEFILE)) + max_size = MAX_NON_LFS; + + if (unlikely(pos >= max_size)) + return -EFBIG; + + *count = min(*count, max_size - pos); + + return 0; } /* @@ -2963,7 +2958,7 @@ EXPORT_SYMBOL(generic_write_checks); /* * Performs necessary checks before doing a clone. * - * Can adjust amount of bytes to clone. + * Can adjust amount of bytes to clone via @req_count argument. * Returns appropriate error code that caller should return or * zero in case the clone should be allowed. */ @@ -3001,10 +2996,6 @@ int generic_remap_checks(struct file *file_in, loff_t pos_in, return -EINVAL; count = min(count, size_in - (uint64_t)pos_in); - ret = generic_access_check_limits(file_in, pos_in, &count); - if (ret) - return ret; - ret = generic_write_check_limits(file_out, pos_out, &count); if (ret) return ret;
The access limit checks on input file range in generic_remap_checks() are redundant because the input file size is guaranteied to be within limits and pos+len are already checked to be within input file size. Beyond the fact that the check cannot fail, if it would have failed, it could return -EFBIG for input file range error. There is no precedent for that. -EFBIG is returned in syscalls that would change file length. With that call removed, we can fold generic_access_check_limits() into generic_write_check_limits(). Signed-off-by: Amir Goldstein <amir73il@gmail.com> --- mm/filemap.c | 33 ++++++++++++--------------------- 1 file changed, 12 insertions(+), 21 deletions(-)